Dual mode terminal for accessing a cellular network directly or via a wireless intranet

ABSTRACT

A wireless intranet office (WIO) concept is disclosed, which integrates an IP based Intranet environment ( 27 ) and GSM network providing mobile telephones ( 21 ) with access to GSM through the GSM network or via the intranet. Access through the intranet to the GSM MSC ( 26 ) is provided by a WIO interworking unit ( 24 ) which may comprise several network entities (e.g. intranet mobile cluster ( 241 ), intranet location register ( 242 ), WIO gatekeeper ( 243 ), WIO gateway ( 244 ) and H.323 gateway). A dual mode terminal for such a system is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/646,419,filed Nov. 30, 2000 which application is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dual mode mobile station operable,for example in a public mobile communication network and a privatenetwork. The Invention also relates to the system in which such a dualmode terminal may operate, and further components of that system.

2. Description of the Prior Art

In modern office work it is necessary to provide the employees withversatile information transfer connections which can transfer speech,facsimile messages, electronic mail and other data—usually in digitalform. Transfer of information is needed inside an office orcorresponding working environment for communication between employees,for transfer of information between branch offices of an enterprise,which offices can be in other towns or even in other countries, and forcommunication between the office and “outside world”. In this text andall of the following text “office” stands for an environment withseveral users, which users “belong together”, and which officephysically covers a reasonably limited area. There has been a trend inthe telecommunication branch toward integrated systems in which variousforms of telecommunication can be controlled as one entity.

A conventional realization of an above mentioned type of officecommunication system comprises a company telephone exchange forproviding telephone services and telephones connected to it overtwisted-pair connections and a separate local area network (LAN) inwhich applications for advanced telecommunication services have beenimplemented and which has the intelligence to run them. The localnetwork is connected to the telephone exchange using a telecommunicationserver (Telephony Server) which supports the traditional subscriberserver architecture in which subscribers are subscribers' computersconnected to the local network. For example call-, data-, facsimile-,electronic mail- and speech mail services are connected within an officeutilizing the telecommunication server. In an integrated system userscan also e.g. control telephone services using their computer terminalsconnected to the local network. The whole integrated officecommunication system is connected to public telephone network throughthe telephone exchange.

FIG. 1 presents an example of a prior known office communication systemin which users' telephones TP (TelePhone) have been connected by wireconnections and a local area network (LAN) has been connected over atelecommunication server TS (Tele Server) into a telephone exchange PBX(Private Branch Exchange) which is connected to a public telephonenetwork PSTN/ISDN (PSTN, Public Switched Telephone Network, ISDN,Integrated Services Digital Network). To the local area network (LAN)have been connected on one hand servers executing various services suchas data base server DBS (Data Base Server), voice server VS (VoiceServer) and electrical mail server EMS (Electrical Mail Server) and onthe other hand the users' computers PC (Personal Computer). It can beregarded as a problem with this kind of realization that even if auser's telephone TP and computer PC usually are on the same table nextto each other separate wire connections must be laid to the user'sworking room for them, on one hand from the telephone exchange PBX andon the other hand from the telecommunication server TS of the LAN.Building and maintenance of two overlapping telecommunication networksnaturally causes cost.

The problem of overlapping telecommunication networks is increased byportable mobile stations utilizing radio connection coming rapidly morepopular. Many persons working in an office need, because of their mobilework, a mobile station and often also a portable facsimile device and/ora combined portable computer/mobile station. In order to be able to usethe devices based on radio connection also inside buildings, theconstructions of which attenuate radio signals, it has been suggestedthat mobile radio networks should be supplemented with small basestations individual for offices or even for rooms, which base stationswould be connected either directly or over wired telephone network tothe central systems of mobile communication network. The network ofsmall base stations would be already a third overlappingtelecommunication network within the same office, and accordingly it isclear that in a preferable solution, which the present invention isaiming at, also the arrangement supporting radio communication stationsshould be realized using essentially the same means andtelecommunication networks than the rest of the transfer of informationin the office.

A challenge of its own to telecommunication systems is issued by thefact that work is done more and more in small office or domesticenvironment, which is described by the concept SOHO (Small Office, HomeOffice). Even here advanced office communication services are oftenneeded and it is particularly preferable if such a flexible system isavailable which can be utilized even both in the office and at home. Thepresent systems which require overlapping connections for theutilization of mobile communication services, conventional telephoneservices and fast data transfer services are very inflexible for workingin a small- or home office. In addition to above, the following kinds ofsolutions connected with integrated telecommunication systems are knownfrom prior art.

If an integrated office communication system is realized utilizingtraditional technique, separate wired connections must be laid into auser's working room on one hand from telephone exchange PBX (FIG. 1) andon the other hand from telecommunication server TS of local area network(LAN). Constructing and maintaining two overlapping networks naturallybrings extra cost. In said solutions according to prior art a solutionto this problem has not actually been striven for.

SUMMARY OF THE INVENTION

The present invention reduces the problems caused by overlappingnetworks. Additionally, the invention reduces problems caused bywireless information transfer inside an office and extra cost. Theinvention is an arrangement, in which said system, integratinginformation transfer, can also serve home office- and small officeusers. The invention is an arrangement of said kind, in which thecarrier devices can be used as terminal devices (e.g. mobile stations)in the telecommunication system both in the office and outside it.

According to an aspect of the present invention, there is provided adual mode mobile station comprising means for managing networkinformation independently of the mode of operation of the mobilestation; first linking means for linking to the interface of a mobilecommunication network so as to transfer control and mobility informationbetween the mobile station and the mobile communication network; secondlinking means for providing a link to the interface of a furthercommunication network so as to transfer control and mobility informationbetween the mobile station and the further communication network; andmeans for coupling the managing means to the first linking means whenthe mobile station is in a first mode and to the second linking meanswhen the mobile station is in the second mode.

This mobile station has common network layer information for both modes(i.e. when the mobile station is within and outside the wirelessintranet office environment). Consequently, as there is no dual stack atthis level, less code is required to implement the dual mode mobilestation, hence making it simpler, faster and cheaper. It Is also easy toimplement the second mode into existing mobile stations as this may beprovided by virtue of a software enhancement to the conventional mobilestation.

The network information is preferably at least mobile communication callcontrol and mobility information. It may also further comprise mobilecommunication radio resources information. However, alternatively, thefirst linking means may comprise a radio resource manager for the mobilecommunication network, and the second linking means may comprise a radioresource manager for the further communication network. This may enablethe mobile station to communicate with an interface on the furthercommunication network by means of simple signalling. For example, thesecond linking means may comprise a radio resource of an unlicensed bandsuch as a low power RF radio resource like Bluetooth.

In a preferred embodiment, the mobile station is further provided with aradio resource manager for a user terminal, and linking means forlinking to the interface of the terminal device so as to transfer radioresource information between the mobile station and the user terminal.Furthermore, a mobile station may further comprise a browser, such as aWAP browser.

According to another aspect of the invention, there is provided a basestation transceiver emulator for interfacing a mobile station of amobile communication network and a further communication network, thebase station transceiver emulator comprising means for determining thepresence of a mobile station within its cell; transceiving means forreceiving call transfer information from the mobile station when themobile station is within the cell and for transmitting call transferinformation to the mobile station as it prepares to leave the cell.

According to a further aspect of the invention, there is provided amobile station emulator for interfacing a mobile station of a mobilecommunication network and a base transceiver station emulator of afurther communication network, the mobile station emulator comprisingmeans for receiving call transfer information from the mobile stationand for forwarding it to the base transceiver station emulator, when themobile station enters the cell of the base transceiver station emulator,means for maintaining the call transfer information while the mobilestation is within the cell; and means for transmitting the call transferinformation to the mobile station as it prepares to leave the cell.

Such an emulator enables simple signalling between the mobile stationand base station transceiver emulator. Furthermore, it enables callforwarding. Moreover, it eliminates the need for a mobile station to beused once it has entered the wireless intranet office environment. Forexample, instead of using a mobile station when in the officeenvironment, a user could use a lightweight terminal such as awristwatch and headset instead, or indeed a PC with headset.

A device for coupling a mobile station of a mobile communication networkto a further communication network may comprise a base transceiveremulator and/or a mobile station emulator. Preferably, the device is apersonal base unit and comprises both of these emulators. Such apersonal base unit may be implemented in a PC.

According to another aspect of the present invention, there is provideda system for transferring information between a mobile station and afurther communication device, the system comprising the mobile station,a communication network to which the further communication device iscoupled, and a base transceiver station emulator for interfacing themobile station and the communication network, wherein the systemtransfers information over the communication network when the mobilestation is within the cell of the base transceiver station emulator, andtransfers information over a mobile communication network when themobile station is outside the cell of the base transceiver stationemulator.

A base transceiver station emulator and mobile station are also providedfor such a system.

Such a system allows users to utilize communication networks, such asprivate intranets to carry cellular services (e.g. speech, data, SMS,facsimile etc.) when within a coverage area. In addition, the WIOconcept provides a good platform for local multi-media extensionsbecause it potentially offers higher bandwidth to the user. Access tothe public cellular network (e.g. GSM) is offered by introducing atransparent location management method, which allows mobile stationsconnected to the communication network, such as the intranet, to bereached from the public cellular network in the normal way. Hence, theconcept can be utilized to provide extra capacity in hot-spot areas,such as airports and malls.

The base transceiver station (BTS) emulator may be an actual basetransceiver station or a virtual base transceiver station. In any event,it is an interface between the mobile station and the communicationnetwork over which the information (e.g., speech, data) is to betransmitted.

The BTS emulator may be the BTS of a mobile cluster. In this event, itis an actual base transceiver station. While a mobile station is withinthis BTS cell, the information to/from the mobile station is transmittedover the communication network, even if there is an overlap with thecell of another public GSM BTS.

Alternatively, the BTS emulator may form part of a personal base unitfor a mobile station, in which case it is a virtual BTS. That is itlooks like a BTS to the mobile communication network, but does nothandover to another BTS.

In one embodiment, where the communication network is an IP network, thesystem takes care of the binding of GSM and IP numbers, so that only onenumber is required. Such E.164=IP# mapping may be performed in the IWU(e.g. by the gatekeeper or ILR, or alternatively in the personal baseunit.

The communication system may be one of several kinds, such as a datacommunication network, internet, intranet, LAN, WAN, ATM packet network,Ethernet (TM), or Token Ring (TM). Also, the further communicationdevice may be one of several kinds, including a PBU, another mobilestation, an MSC or an FSC.

The mobile station and PBU may be connected by RS232 cable.Alternatively, they may have an RF (preferably LPRF) or infraredconnection. Examples include Bluetooth, Home RF, 802.11 WLAN etc. Also,they may be indirectly connected, for example via a connection devicesuch as a mobile station cradle, deskstand or charger, or even a LAN ofsome kind.

According to another aspect of the present invention, there is provideda dual mode mobile station comprising control means for controllingtransfer of information such that in a first mode transfer ofinformation is between the mobile station and a mobile communicationnetwork, and in a second mode transfer of information is between themobile station and a second communication network, and means forproviding radio contact between the mobile station and the mobilecommunication network in both the first and second modes.

The first mode is, for example, when the mobile station is outside theoffice environment and the second, when it is within it,

In a preferred embodiment, the control means and means for providingradio contact are realized by virtue of a software enhancement toconventional mobile terminals. Hence, the terminals are much simplerthan existing dual mode terminals, which, for example, require switchesto change between the modes. Also, the terminal of the present inventionremains connected to the mobile network while the actual data(data/speech etc.) is carried over another interface. Thus it providesthe mobile network with what seems to be the same operation specifiedfor the standard mobile communication network entities.

Now a system has been invented for transfer of information, e.g. speechor data, in which the trunk of information transfer is inside the officea local network (e.g. local area network, LAN), and between office unitse.g. a traditional telephone network utilizing wired connections or afast data packet network utilizing ATM (Asynchronous Transfer Mode)technique, for example.

According to one embodiment of the invention the mobile station may beconnected to the terminal device by means of a connection device, havinga functional connection to the terminal device, and having means forconnecting functionally to the mobile station. In response to connectinga mobile station to the connection device, the system will be informedto direct calls to the mobile station via the data communicationnetwork. The connection device can be a desktop stand or desktop chargerand may be a separate device or integrated into the terminal device.

A subscriber device means a terminal device connected to atelecommunication network, such as a telephone connected to a fixedtelephone network, and a mobile station connected to a mobilecommunication network. A subscriber device also means servers andtelephone exchanges connected to telecommunication networks, providingtelecommunication services to the users of the telecommunicationnetworks. In other words, a subscriber device means all the parts of atelecommunication network with which a telecommunication terminal device(e.g. a telephone) can communicate over a telecommunication network.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample, with reference to the accompanying drawings, of which:

FIG. 1 presents traditional communication networks and terminal devicesused in an office environment;

FIG. 2 illustrates a wireless intranet office architecture according toan embodiment of the present invention;

FIG. 3 illustrates a wireless intranet office architecture according toan embodiment of the present invention;

FIG. 4 illustrates the architecture of a mobile station and personalbase unit of a wireless intranet office, according to an embodiment ofthe present invention;

FIG. 5 illustrates a general GSM intranet office concept;

FIGS. 6 to 11 show information flow from terminals of a GSM intranetoffice according to an embodiment of the present invention;

FIG. 12 illustrates the architecture of a mobile station according to afurther embodiment of the present invention;

FIG. 13 illustrates a wireless intranet office system according to anembodiment of the invention in which the user is provided with ahandsetless user terminal which communicates with his mobile station;

FIG. 14 illustrates a wireless intranet office system according to afurther embodiment of the present invention, in which the user isprovided with a handsetless user terminal which communicates directlywith the personal base unit; and

FIG. 15 is a flow chart illustrating the functioning of a virtualterminal in the embodiment of FIG. 14, and

FIG. 16 illustrates the handling of an electronic book service within awireless intranet office.

FIG. 2 illustrates a wireless intranet office architecture according toan embodiment of the present invention.

As can be seen, the wireless intranet office integrates an IP basedprivate intranet environment with a public cellular network, in thiscase the GSM network. This allows cellular users to utilize privateintranets to carry the cellular services (i.e. speech data, SMS,facsimile, etc.) within the intranet coverage area. In addition, thewireless intranet office architecture provides a good platform for localmultimedia extensions because it potentially offers higher bandwidth tothe user. Access to public GSM network is offered by introducing atransparent location management method, which allows terminals connectedto the intranet to be reached from the public GSM network in the normalmanner. Thus, the wireless Intranet office arrangement can be utilizedto provide extra capacity in hot spot areas, such as airports, mallsetc., where this might be needed.

In this wireless intranet office arrangement, the intranet forms a newkind of access network to the GSM network. The communication between theGSM backbone network and the end user access node takes place viainternet protocol based networks instead of the GSM air interface, aswill be seen below,

FIG. 2 shows a mobile station 21 in a wireless intranet officeenvironment. When outside this environment, the mobile station acts as anormal GSM phone connecting to a BTS of a public GSM network. However,when in the wireless intranet office environment, the mobile station mayoperate on one of two modes. In one mode, it connects to a personal baseunit 22 (e.g. either with a inter-connection cable, a infraredconnection, or with low power RF transmitter and receiver), and inanother mode connects to a GSM base transceiver station (BTS) 23. Themobile station 21 is connected to an IP local area network (LAN) and ahome location register (HLR) and visitor location register (VLR) 25 anda mobile station controller (MSC) 26 by virtue of an inter-working unit(IWU) 24. This IWU comprises several network entities, including anintranet mobile cluster (IMC) GSM/IP Gateway 241, an intranet locationregister (ILR) 242, a WIO gatekeeper 43 and a WIO A-gateway 244.

Information such as data and/or speech may be transferred from themobile station to the IP local area network by two routes, each of whichincludes a BTS emulator. In a first mode, the mobile station 21 isconnected to the local area network via a personal base unit 22 (PBU),which itself comprises a virtual BTS. This is further explained withreference to FIG. 4 below.

In a second mode, the mobile station 21 forms part of a mobile cluster(for example see reference 32 in FIG. 3). In this case, the informationis transmitted to the local area network via a private GSM BTS 23dedicated to that cluster, and an IMC GSM/IP Gateway 241. The BTStransmits the signal over the A bis interface, and the IMC Gateway 241performs a protocol transform from GSM to H.323, so that the signal canbe transmitted over the IP local area network. (As can be seen from thisfigure, the wireless intranet office architecture uses the H.323protocol for the signalling and data connections inside theinter-working unit).

The basic access interfaces to the cellular network are the airinterface, the A-interface, the MAP protocol, the ISUP/TUP interface andthe DSS.1 interface. The A-interface is an interface to mobile switchingcenter and the MAP interface is an interface to HLRNLR. ISUP/TUPinterface connects switching centers, while the DSS.1 interface residesin between the BSX and switching center. The air interface connectingmobile terminals to the network can be any RF interface or infraredlink. Candidate RF interfaces include e.g. Low Power RF (LPRF), 802.11,wireless LAN (WLAN) WATM and HIPERLAN. The air interface can also bereplaced with a physical connection (e.g. RS-232 serial cable orUniversal Serial Bus (USB). The GSM network sees this new access networkas a BSS entity. New network entities are added to the access network tomodify/de-modify cellular signalling. System design principle is tofulfill ITU-T's recommendation H.323 and enhances it with mobilityextensions.

The WIO A-gateway 244 looks like a base station controller to the MSC26.

A general WIO network architecture is shown in FIG. 3. A local areanetwork 31 is provided with an intranet mobile cluster IMC 32, an LPRFcell 34 and a landline connection 35. The IMC comprises a plurality ofmobile stations, a BTS (private GSM BTS) and a server in the form of anIMC GSM/IP gateway. The BTS interface between the BTS and IMC GSM/IPgateway is a GSM A-bis interface. The IMC GSM/IP gateway is responsiblefor signalling conversions between the GSM and H.323 protocols. The lowpower RF cell 34 comprises a personal base unit which has a virtual BTSand a low power transceiver, and associated mobile stations withcorresponding low power RF transceivers. The PBU is directly connectedto the WIO network. To provide the mobile stations with access to theGSM network, the PBU provides conversions between the GSM and H.323protocols. These conversions can be seen as a bridge between cellularphone and H.323 features which support WIO location management andmobility features. The landline connection comprises a landline terminal351 hardwired to a personal base unit 352, which in turn is hardwired tothe local area network.

Also connected to the local area network are a WIO gatekeeper 36, whichis responsible for the connection of mobile stations to within andoutside the network. For example it might transfer a call from theserver to an external system such as PSTN (via gateway 38) or it couldprovide connection to the IP network 37. The IP network, in turn, isconnected to the operators local area network 39. This local areanetwork is provided with an A-intranet gateway 391, an intranet LocationRegister 392 and IP telephony gateway 393.

In this embodiment the main function of the Intranet Location Register392 is to store mobility management information and call statistics ofthe subscribers configured into the Wireless Intranet Office system.Roaming of visitors is controlled by the mobile switching center. Forvisitors only temporary information will be stored into the IntranetLocation Register.

The ILR has a MAP interface to cellular system network HLR 25.

The IP Telephony Gateway 383 in this embodiment supports interworkingbetween Internet telephony endpoints and mobile stations in the publiccellular network. The interworking is based on the H.323 specifications.

The A-Intranet Gateway 391 in this embodiment makes protocol conversionbetween SCCP/MTP and IP protocols at the A-interface, and makes thecellular and Intranet location area associations. It has an O&M softwareentity which operates as an administrative server gateway forcorresponding agents in intranet mobile clusters. The A-intranet Gatewayoperates as a firewall between public telecommunication network andprivate intranet solutions,

Further explanation of the network entities in FIGS. 2 and 3 areoutlined below.

The Intranet Mobile Station is a generic terminal product portfolioconsisting of full-featured cellular phone which supports services ofGSM and GSM derivatives. It may have specific features such as extendedoffice/home cell selection criterias, and support of office and homearea priority. With a serial cable and with a piece of software to a PC,intranet mobile station—so called LANdline version—enables seamlesslandline communication to cellular system network and between otherInternet telephony entities within IP network. It may be a GSM/LPRFdual-mode device enabling high value services within certain serviceareas.

The Personal Base Unit (PBU) may be a PC Card type of radio card for adesktop PC with a piece of software enabling wireless access to IPnetwork. It provides LPRF cordless and wireless LAN—on 2.4 GHzband—dual-mode access exploiting an unlicensed radio spectrum. Incordless, “unlicensed” mode lower layers will be replaced with new ones,but signalling above them remains the cellular one. It also enablesintelligent roaming of terminals between different radio frequencybands, i.e. between cellular and unlicensed bands.

The Intranet Mobile Cluster is simulating BSC in a local environment. Itconsists of minimum set of BTS functionality with reduced physicalconstruction. Intranet mobile cluster is a BTS arid a BTS driversoftware package for Windows NT 5.0 including rate adaptation, an O&Magent software package and a GSM/IP telephony gateway entity. Intranetmobile cluster provides interworking with data services and facsimile asa direct access to IP network, and it may provide local call routingcapability within its radio coverage.

The purpose of the GSM/IP Telephony Gateway is to reflect thecharacteristics of an Internet telephony endpoint to an Intranet MobileStation, and the reverse, in a transparent fashion. The GSM/IP telephonygateway provides appropriate format translation of signalling andspeech. i.e., audio format translations between GSM 06.10, 06.20, 06.60,J-STD-007 and G.711, G.723 and transformation of communicationsprocedures. The gateway performs call setup and clearing on both theInternet telephony side and the Wireless intranet office side.

The MS-IP (WIO) gatekeeper 36,243 provides mobility and call managementservices, and certain radio resource management functions.

The MS-IP gatekeeper provides the following services:

Registration control—The MS-IP gatekeeper authenticates all the networkentities, i.e., intranet mobile stations, intranet mobile clusters,A-intranet gateways, IP telephony gateways, intranet location registers,H.323 terminals, which have access to the system. In case of intranetmobile station, authentication and registration is based on automaticGatekeeper discovery procedure. In other cases, it's based on manualgatekeeper registration procedure.

Connection ciphering—Part of the gatekeeper's authentication procedureis connection ciphering service. It provides key distribution,identification and encryption/decryption services to the gatekeeper andother entities in the system. Service has an option to select ciphering,hashing, key distribution and signature algorithms independently. Keydistribution is based on public key cryptography and message cipheringis based on secret key cryptography.

Address translation—The MS-IP gatekeeper performs E.164 to transportaddress association and translation. This is done using directoryservice in the intranet location register which is updated duringmobility management procedures, i.e., during TMSI reallocation,authentication, identification, IMSI detach, abort, and locationupdating.

Call control signalling—The MS-IP gatekeeper can be configured to routecall control signalling to the cellular system network or to the localcall management entity within the gatekeeper.

Call management—The MS-IP gatekeeper maintains also list of ongoingcalls and collects call statistics. This information is stored into theintranet location register by the gatekeeper.

Cellular procedures—The MS-IP gatekeeper must be able to handlesignalling and resource management procedures (BSSMAP resources)specified in GSM recommendation 08.08.

Status control—In order for the MS-IP gatekeeper to determine if theregistered entity is turned off, or has otherwise entered a failuremode, the MS-IP gatekeeper uses status inquiry to poll the entity at acertain interval.

The MS-IP gatekeeper may, for example comprise software which uses aWindows NT platform together with some dedicated hardware in the IMC andgateways to fulfill the ITUT's H.323 gatekeeper specifications, extendedwith certain mobility management capabilities according to GSM 04.08.

FIG. 4 shows the architecture of a mobile station 41 and a personal baseunit, personal computer 42, according to an embodiment of the presentinvention.

The mobile station 41 and personal base unit 42 are represented showinglayers 1 to 3 of the 7 layer OSI reference model, namely physical layer(layer 1), data link layer (layer 2) and network layer (layer 3). (Theseare data communication protocols whose purpose is to provide a linkbetween 2 communicating devices).

Network layer 43 of the mobile station 41 provides call controlmanagement 431 (including supplementary services 435 and short messageservices 436). This layer also provides mobile management 432 and radioresource management 433. Further, It comprises a MUX which “switches” toa second branch of layer 2 to demand services of the data link (phonebus FBUS) Ctrl 443) and physical layer (FBUS 452) when the mobilestation 41 and the personal base unit 42 are “connected”. In any event,the network layer demands the services of the data link layer 44 (datalink 441 and control 442) and the physical layer 45 of the first branch,to allow the mobile station 41 to perform and report its measurementsabout the surrounding GSM network (neighboring BTSs) and thus complywith GSM requirements.

Turning now to the personal base unit 42, this PBU comprises a phonedriver implementing the physical and data link layers 48 and 47 (FBUS481 and FBUS ctrl 471). The network layer 46 of the PBU comprises a PBUcontrol/IMC core control 462 and an H.323 protocol entity 463 whichprovide protocol conversion between GSM and H.323. The conversions areneeded for GSM layer 3 signalling messages while the speech is carriedas GSM coded in the whole while this intranet office network. The PBUfurther comprises TCP/IP entity 422 and a local area network adapterdriver for the 23 for interfacing with the local area network. The PBUcontrol 462 comprises a virtual BTS 49 for communicating with thenetwork layer 43 of a mobile station 421.

This figure shows layers 1 and 2 of the second branch of the mobilestation and the PBU as a phone bus (FBUS). This is because, in thisembodiment an RS 232 serial connection is used. However, it is evidentto a person skilled in the art that these layers would be implementedusing different technologies if, for example, connection is via IR orRF.

The mobile phone also has a user interface 461.

In the network, the mobile station interlaces the intranet mobilecluster and personal base unit entities. The interface to the personalbase unit, as can be seen from FIG. 4, uses a modified GSM layer 3(04.08) signalling in this embodiment. (However, in an alternativeembodiment, shown in FIG. 12, the GSM radio resource is not delivered tothe PBU from the mobile station. Instead, Bluetooth radio resourcingreplaces it as a consequence of part of the virtual terminal beingimplemented inside the mobile station control software).

The mobile station 41 and PBU 42 operate as follows.

When the mobile station 41 is outside the wireless intranet officeenvironment, it operates as a normal GSM phone. The MUX 434 does notcouple the radio resource management entity 433 with the second branch443, 452. Voice and signalling is transmitted via the data link layer 44and physical layer 45 over the first (GSM) branch to the cellular airinterface.

Also, if the mobile station 41 is within the wireless intranet office,but forms part of an intranet mobile cluster, this same path is taken tothe cellular air interface and the information and signalling istransmitted to the GSM BTS of that cluster.

However, when the mobile station 41 is connected to a PBU 42 (forexample by an RF 232 serial cable or RF interface) information such asvoice, data, fax, SMS etc., is transmitted over the local area network.In this case, the MUX 434 demands the service of the second (LAN) branchlayers 1 and 2, and layer 3 of the mobile station 41 is seen tocommunicate with the virtual BTS 49 of the PBU 42. That is, theinformation (e.g. speech) and GSM layer 3 signalling messages areredirected to the second branch interface. As the mobile station 41 andthe PBU 42 are linked, the field strength of the virtual BTS 49 will begreater than that of other BTSs in the GSM network. Consequentlyhandover is made to the virtual BTS 49. After this, the handoversignalling relating to this virtual BTS is handled from the MUX throughthe second branch. When handover has been made, the MUX handles allmessages and forwards them to the new host cell through the RS 232interface etc and “talks” to the other BTSs (as is conventional in GSM)over the first branch. General broadcast traffic is also seen by themobile station 41, for example from layers 1 and 2 to the MUX and fromthere through the mobile station/PBU interface to the virtual BTS 49.

While in this mode, the speech and layer 3 signalling are routed to thepersonal base unit, and the radio resource management entity at layer 3remains connected to the GSM layer 2 (441), that is branch 1. Asmentioned above, this is so that the mobile station can act as requiredby GSM (for example by measuring the RSSI for neighboring BTSs etc.).

The parameters in the virtual BTS 49 within the IMC core are set in sucha manner that the terminal is forced to remain clamped to this virtualOSM cell. This avoids possible handovers to any other GSM cells themobile station might hear.

The operation of the MUX can also be explained as follows. When themobile station changes to “LANdline” mode (for example when the otherinterface is connected), the MUX communicates with the new BTS in asimilar way to as it does to other BTSs to which it is not connected. Inthis phase, the mobile station notices that the field strength of thenew BTS relating to this new interface is more powerful than the fieldstrength of other BTSs, and hence makes the handover to this BTS. Afterthe handover, signalling relating to the new BTS are handled by the MUXthrough the new interface, and the mobile station keeps on listeningthese and sends measurement reports to virtual BTS general broadcasttraffic is also sent to the new mobile station, for example from thelower stage to the MUX and from there through the new interface to thevirtual BTS.

FIG. 5 shows a general GSM intranet office concept, and FIGS. 6 to 11show information flow between terminals—FIGS. 6 to 9 being within theoffice environment and FIGS. 10 and 11 extending to outside theenvironment.

FIG. 5 shows the GSM intranet office 57 comprising different terminalarrangements 51 to 54. The intranet office interfaces with an internetprotocol network 58, which is partially situated within the office andpartially at the operators location. The operator 59 controls transferof information between the IP network 58 and network switching centers,such as mobile switching centers 55 and fixed line switching centers 56.

Terminal arrangements 51 and 52 comprise a mobile station 51 a, 52 a anda BTS emulator 51 b, 52 b. These mobile stations can be within anintranet mobile cluster or can be coupled to a personal base unitcomprising a virtual BTS.

FIG. 6 illustrates a call between mobile stations of the same office. Inthis case, the call might be sent by mobile station 51 a to mobilestation 52 a. The information is transmitted from mobile station 51 a toBTS emulator 51 b and on to the LAN via the inter-working unit. Thelocal area network then transfers the information to BTS emulator 52 bwhich in turn forwards it to mobile station 52 a.

FIG. 7 shows a call between a mobile station 51 a and an H.323 terminal54 within the same office. Information transferred from mobile station51 a will be forwarded to the LAN in the same manner as in FIG. 6 (i.e.via BTS emulator 51 b and the WIO inter-working unit). The LAN thentransfers the information to the terminal 54.

FIG. 8 shows a call between a mobile station 52 a and a fixed lineextension 53 a of a private branch exchange 53 b of the same office.Again, information is transferred from mobile station 52 a to a localarea network via BTS emulator 52 b and the office IWU. The informationis then transferred over the local area network via a PSTN gateway toPBX 53 b. This PBX then switches the information to the requisiteextension 53 a.

FIG. 9 shows a call between a H.323 terminal and a PBX extension of thesame office. In this case, there is no GSM connection. Information isforwarded to the local area network from the terminal 54 where it istransferred to PBX 53 b via the local area network on a PSTN gateway.The PBX 53 b then switches the information to the requisite extension 53a.

FIG. 10 shows a call between a mobile station 51 a of the WIO to themobile network. In this case, information is transferred from mobilestation 51 a to the local area network via the BTS Emulator 51 b and theinter-working unit. It is then transferred across the local area networkand to a mobile switching center 55 via an A-gateway.

FIG. 11 shows a call between a mobile station 52 a of the WIO and afixed line network. In this case, information is transferred from mobilestation 52 a to the local area network via BTS emulator 52 b and theinter-working unit. The information is then transferred over the LAN toa fixed line switching center 56 via a PSTN gateway.

In the information transfer system according to the invention,information transfer connections based upon ATM and GSM technologies maybeen utilized. Furthermore, it is fully possible to utilize instead ofthese techniques other kinds of information transfer connections. Forexample it is possible to arrange, instead of the ATM system, theinformation transfer connections between terminal devices 40 to 43,teleservers 60, 61 arid network server 90 entirely e.g. using systemsbased upon Ethernet and Token Ring or future wide band networks.Correspondingly it is possible to realize, instead of GSM-system, aninformation transfer system according to the invention even inconnection with other mobile communication systems, such as e.g. TDMA(Time Division Multiple Access), CDMA, W-CDMA AMPS (Advanced MobilePhone Service) and NMT (Nordic Mobile Telephone) systems.

Moreover, it can be transferred over WATM, 802.11 and mobile IP, whichallows the network entities (PBU, IMC, etc.) being mobile. This enables,for example, forming a WIO cluster/IMC into a train or airplane.

FIG. 12 shows the architecture of the mobile station 120 according toanother embodiment of the present invention. This mobile station isprovided with both GSM and LPRF (Bluetooth) parts (processors, RF partsetc.), and communicates with the public mobile network using GSM, andthe PBU of the WIO network using LPRF (Bluetooth). An example ofcommunication using Bluetooth is described below with reference to auser terminal and PBU in FIG. 14.

The mobile station 120 of this embodiment is represented showing layers1 to 3, namely physical layer (layer 1) 121, data link layer (layer 2)122 and network layer (layer 3) 123.

Network layer 123 of the mobile station 120 provides call controlmanagement 124 (including supplementary services 124 a and short messageservices 124 b) and mobile management 125. That is, these layer 3network management services are common to both GSM and Bluetooth modesof operation. This network layer further comprises a multiplexer, MUX127, which demands services of the layer 3 radio resource management 126and also of the lower layers 121, 122. In this embodiment the MUX 127connects to a second branch of layer 3, to the Bluetooth radio resourcemanagement 126 b, to demand services of the Bluetooth radio resourcemanagement 126 b, data link (DL and CTRL 128 b, 128 d) and physicallayer 129 b, when the mobile station 120 is within the wireless intranetoffice environment. The call control and mobility management functions124 and 125 of the network layer also demand the services of the GSMradio resource management part 126 a, the data link layer (DL CTRL 127a, 128 a) and the physical layer 129 a of the first branch via the MUX127. This allows the mobile station 120 to perform and report Itsmeasurements about the surrounding GSM network (neighboring BTSs) andthus comply with GSM requirements and also to communicate with a virtualBTS within the WIO if applicable.

When the mobile station 120 Is outside the wireless intranet office, thecommon network layer functions demand the services of the layer 3 GSMradio resource management 126 a and services of the lower layers 128 a,128 c, 129 a of the first branch (GSM branch).

FIG. 13 illustrates a wireless intranet office arrangement according toanother embodiment of the invention.

In this arrangement, a mobile station 131 connects to a PBU 132 whichmay, for example, be a personal computer. The PBU 132 comprises a BTSemulator in the form of a virtual BTS 133. A radio connection is shown(e.g. infrared or LPRF) between the mobile station and PBU, but theconnection may be a different type such as a wired connection. Themobile station 131 is connected to an IP LAN 135 and mobilecommunications network 136 by virtue of an IWU 134. The IWU may compriseseveral entities such as a GSM/IP gateway, an intranet locationregister, a WIO gatekeeper and a WIO A gatekeeper, as mentioned abovewith reference to FIG. 2. Rather than having to carry the mobile stationaround, the user is provided with a user terminal in the form of awireless headset 137 and wristwatch user interface 138. The wirelessheadset 137 connects to the mobile station 131 over an air interfaceusing LPRF remote audio protocol (e.g. Bluetooth), and the wristwatch UI138 is similarly connected over the air interface using LPRF remote userinterface protocol (e.g. Bluetooth).

The mobile station 131 of this embodiment, like that of FIG. 12 has bothGSM and LPRF (e.g. Bluetooth) parts. However, as explained above, inthis embodiment Bluetooth is used for communication between the mobilestation 131 and the user terminal 137, 138, as opposed to between themobile station 131 and PBU 132. Consequently, the mobile station'sprotocol stack will differ from that shown in FIG. 12. Morespecifically, the Bluetooth physical layer 129 b will couple to the airinterface of the user terminal as opposed to that of the PBU. Moreover,layers 1 and 2 of the GSM protocol stack will be distinguished. That is,this first branch 127 a is further divided by the provision of a MUXbetween layers 2 and 3 as shown in FIG. 4, depending on whether aninterface is required to a GSM BTS or to a virtual BTS within a WIOenvironment.

When the handset 131 is outside the wireless intranet officeenvironment, the handset 131 operates as a normal GSM phone. That is,MUX 127 connects to the GSM radio resource management 126 a and the GSMlower layers 121 and 122 to obtain connection to a public GSM BTS. Theother layer 1 and 2 stack linking to the virtual BTS would bedisconnected as described above with reference to FIG. 4.

Optionally, the MUX 127 may also make connection to the Bluetooth radioresource management 126 b, for example if the user selects an option touse user terminals 137, 138 within the GSM environment.

When the handset enters the wireless intranet office environment, on theother hand, the MUX 127 may effect a connection so that the call controland mobility management functions may demand services of the Bluetoothradio resource function and layers 1 and 2, 126 b, 128 b, d, 129 b,either automatically or upon user selection. Such connection enables theprovision of a communication channel between the mobile station 131 andthe user terminal 137, 138. To effect a link between the mobile stationand PBU 132, the MUX 127 connects the GSM radio resource function 126 ato the common layer 3 functions, namely call control 124 and mobilitymanagement 125. The GSM radio resource function 126 will demand serviceof layers 1 and 2 of the stack for linking with the PBU when in thiswireless intranet office environment. Further, the GSM network willrequire signalling updates. Hence, layers 1 and 2 linking to both theGSM, BTS air interface and PBU air interface are connected.

FIG. 14 shows an alternative embodiment of the invention, in which userterminals 137, 138 communicate directly with a personal base unit, whenin the wireless intranet office environment. The system is similar tothat shown in FIG. 13, but with one major difference. When the mobilestation 131 is in the wireless intranet office environment, itsfunctionality is transferred to the PBU 132. That is, the PBU 132 thencomprises a virtual mobile station 139, as will be explained furtherbelow. As a consequence, the user terminal 137, 138 can communicatedirectly with The PBU 132, thereby eliminating the need for the mobilestation to remain turned on.

When the mobile station MS changes over to the WIO mode, the mobilestation 131 transfers the dynamic data relating to the state of themobile station and the calls in progress to a virtual terminal vMS 139,which is established in the PBU 132.

This data is maintained in a state machine, which is located in thevirtual terminal. In this context, the state machine means a functionalentity that describes the allowed changes in the state relating to thefunctioning of the mobile station and the related messages according tothe protocol. The functionality described by the state machine maintainsthe data on the possible changes in the state relating to said protocollayer, the instantaneous state, the data structures relating to thechange in the state, etc. Thus, a state machine in connection with theGSM means the mobile station's functionality related to the mobilestation's GSM Layer 3 protocol (NULL, current switched on, switched to abase station, etc.) In addition, said state machine in the higher levelmaintains a partial state machine for the mobile station's everyconnection, whereupon the state of the connection can be, for example,NULL, call initiated, call proceeding, active, etc.

The protocol stack of the virtual terminal vMS in PBU may comprise theGSM functionality described by a state machine 105, which comprises atleast a radio resource (RR), mobility management (MM) and callmanagement (CM), i.e. functions related to protocol layer. It may alsocomprise an additional protocol 106 relating to communication betweenthe PBU and the user terminal operating in the WIO mode (e.g. theBluetooth functionality). This will be discussed later in more detail.

When the PBU 132 has the use of the data of the state machine, the PBUstarts the virtual terminal vMS 139, which emulates the functioning ofthe actual mobile station MS towards the mobile communication system. Itreceives signals from the mobile communication network and, on the basisof the status data it maintains, it carries out signalling towards themobile communication system, either independently, or according to theinformation it requests from the user terminal UT in WIO made. It shouldbe noted that since the state machine during WIO mode is maintained bythe virtual terminal, the signalling to be implemented in differentdirections is independent, which means that changing of the protocol ineither direction does not interrupt the functioning of the virtualterminal.

The flow diagram presented FIG. 15 illustrates the functioning of avirtual terminal on the basis of a message arrived from a mobilecommunication network. In step 110, the virtual terminal VMS 139receives a message from the mobile communication network MOB. In step111, the virtual terminal vMS compares the contents of the message tothe state machine it maintains and, on the basis of it, defines themessage required for changing over to the next state. In step 112, thevirtual terminal defines whether a connection to the user terminal UTthat operates in the WIO mode is required for generating the nextmessage or whether the required data is available in the inter-workingunit. If a connection to the user terminal UT is necessary, the virtualterminal generates the message relating to said function (step 113) andsends it through the IP network to the user terminal UT (step 114). Atthe same lime, it updates the state of the process in question to thesignalling state maintained by it (step 115). If no connection to theuser terminal UT is required and the virtual terminal concludes that thenecessary signalling can be managed by itself, the virtual terminalchecks whether the subscriber information stored in the PBU is requiredfor the reply or whether the reply message can directly be generated onthe basis of the status data (step 116). If additional information isrequired, the virtual terminal retrieves it from PBU's memory (step 117)and, on the basis of it, generates a message to be transmitted to themobile communication system (step 118). If no additional information isrequired, the virtual terminal generates a message in accordance withthe mobile communication system's protocol defined on the basis of thestatus data (step 118). In step 119, the message generated by thevirtual terminal is transmitted to the mobile services switching center.At the same time, the virtual terminal updates the state of the processin question in the state machine it maintains (step 115).

One way of managing a connection between the virtual terminal vMS 139and the user terminal UT in WIO mode is to convert the GSM signallinginto packets in accordance with the IP and to transfer the signalling tothe user terminal UT in the GSM format. Anyhow, information transferredbetween the mobile communication network and the user terminal UTincludes a lot of signalling relating to the use of a radio resource.Such traffic in the arrangement according to the invention issubstantially unnecessary. Hence, in this embodiment, a connection ismanaged by simplifying the protocol during WIO operation. This kind ofprotocol can be established, for example, by selecting a group of ATcommands, which are transported between the vMS and the MS in WIO mode.For the establishment of a connection, a simple, manufacturer-specificprotocol can also be defined.

The implementation of said protocol could be illustrated by giving anexample of the different functions, which are needed for communicationbetween the vMS 139 and the UT in WIO mode. These include, for example,the functions 1.1.-1.7. listed In the first column of Table 1. Thesecond column of Table I contains a functional description of messages.TABLE I Reference Function Messages 1.1 Making of Call Request to CallMS->vMS Resetting of Request to Call vMS->MS 1.2 Reception of CallIndication of Call vMS->MS Resetting of Indication of Call MS->vMS 1.3Speech Transport of Coded Speech Over UDP 1.4 Ringing Out Request forSwitching Off/Indication 1.5 SMS SMS Transmission/Reception 1.6 FAXTelecopy Transmission/Reception 1.7 Handover Handover MessageTransmission/Reception (State Machine)

When a subscriber wants to make a call (1.1), a user terminal UT makes arequest for a call and receives the message of the setup of the callgiven by an vMS, before the transfer of the data relating to the callbegins. When the subscriber receives a call (1.2), the user terminal UTreceives the message of the incoming call from the vMS and informs thevMS of the reception of the call before the transfer of the datarelating to the call begins. When either the subscriber or the otherparty wants to cut off the call (1.3), the user terminal UT gives orreceives a request to cut off the call. On the basis of the protocol,both the user terminal UT and the VMS should be able to distinguishwhether it is a question of the transfer of speech (1.4), a shortmessage (1.5) or telecopied data (1.6). The message 1.7 contains thestatus data on the calls in progress, which are transported when thevirtual terminal is taken into use or when the use of the virtualterminal is terminated as described above.

The above-mentioned command group is only one possible way ofimplementation. For example, making a call can be arranged so that theuser terminal UT identifies, on the basis of the first speech packets,that a call is coming in, in which case not even a separate call phaseis required. Correspondingly, the vMS can automatically adapted to cutoff the call when the reception of the call packets from the userterminal UT stops. With a simple command group, it is possible toimplement adequate functions by means of which the user terminal UT thatoperates in the WIO mode can utilize the mobile communication network'sservices, though part of the signalling is managed elsewhere.

Referring back to FIG. 14, when a user enters the office carrying histraditional user terminal UT handset, the phone indicates that LPRF LANaccess is available. When the subscriber so wishes, he/she can e.g. plugthe handset into an intelligent charger such as described in PCTPublication Number WO98/15143, and thus enable “handsetless operation”using merely the wrist UI and wireless headset. In such an operation,the traditional terminal is inactive and the virtual terminal acts as amobile station towards the mobile communication network. The trafficbetween the lightweight terminal and the virtual terminal is carried outthrough LPRF connection using the specific protocol layer as describedearlier. While in the office, he/she can walk around the LPRF coveragearea and use GSM services without the handset When leaving the officehe/she can enter normal cellular operation by just taking his/herhandset along and even continue the ongoing call. The invention thusfacilitates a completely wearable communications device in officeenvironment with the user identified as the same mobile subscriber asoutside office with handset. The phone numbers, user setting,personalized features etc. will remain in both operating modes.

FIG. 16 illustrates the handling of an electronic book service within awireless intranet office, according to a preferred embodiment of theinvention. The system may utilize a dual mode terminal of the inventionas is shown for example in FIG. 12. Mobile data services are becomingincreasingly prevalent from mobile communications operators. One suchservice may be electronic book (E-book) purchasing. In this embodiment,E-book purchasing 161 is available through the operator of a mobilecommunications network 162. The user of mobile station 160 can accessthis service either via the public mobile network 162, or via the WIO.In the latter case, connection to the mobile network 182 is via PBU 166and IWU 165 as explained with reference to FIG. 2 above. Similarly, thebook required may be downloaded via the public or private networks. Inthe event that the mobile station 160 is within the public mobilecommunications area 162 but outside the WIO environment, the book may bestored in the mobile station's memory (or if the mobile station is aportable computer with data card, then it may be stared an thecomputer's hard disk, for example). Ideally, this is a temporarymeasure, and the book can subsequently be transferred for storage withinthe WIO network when the mobile station enters the WIO environment. Forexample, the user could choose to store the E-book on his PC (PBU 166),or alternatively in an office library 163 of the offices IP LAN 164.Alternatively, if the mobile station is within the WIO environment, theuser may request the E-book via the WIO network, and the book mayautomatically be downloaded to the requested WIO device (e.g. officelibrary 163, or users PC). An advantage of storing an E-book in theoffice library 163 is that it is accessible to other users of theoffice. Consequently, if the user's terminals (mobile station, PC etc.)have a suitable browser, the user can search through books, newspapersetc. for desired information. If the user's terminal is a PC, then aconventional IP browser may be used. Alternatively, if the user'sterminal is a mobile station 160, such as a mobile phone, then it ispreferably provided with a WAP browser so that it may search thecontents of the library 163, over a tow power RF interface 167 such asBluetooth.

The above is a description of the realization of the invention and itsembodiments utilizing examples. It is self evident to a person skilledin the art that the invention is not limited to the details of the abovepresented embodiments and that the invention can be realized also inother embodiments without deviating from the characteristics of theinvention. The presented embodiments should be regarded as illustratingbut not limiting. Thus the possibilities to realize and use theinvention are limited only by the enclosed claims. Thus differentembodiments of the invention specified by the claims, also equivalentembodiments, are included in the scope of the invention.

For example, while the embodiments refer to intranet offices, it is notrestricted to the intranet, but is also applicable to the internet.

1. A dual mode mobile station comprising: managing means for managinginformation independently of the mode of operation of the mobilestation; first linking means for linking to the interface of a mobilecommunication network, said first linking means comprising a radioresource manager for the mobile communication network; second linkingmeans for providing a link to the interface of a further communicationnetwork, said second linking means comprising a radio resource managerfor the further communication network; and means for coupling themanaging means to the first linking means when the mobile station is ina first mode and to the second linking means when the mobile station isin the second mode such that the mobile station remains connected to themobile communication network, while actual data is carried over thefurther communication network.
 2. A mobile station as claimed in claim1, wherein the managing means further manages radio resourcesinformation independently of the mode of operation of the mobilestation.
 3. A mobile station as claimed in claim 1, wherein the secondlinking means comprises a low power RF radio resource.
 4. A mobilestation as claimed in claim 3, wherein the low power RF is Bluetooth. 5.A mobile station as claimed in claim 2, wherein the radio resourcemanagement is that the mobile communication network.
 6. A mobile stationas claimed in claim 1, wherein the call control and mobility managementis that of the mobile communication network.
 7. A mobile station asclaimed in claim 1, wherein the mobile communication network is GSM. 8.A mobile station as claimed in claim 1, further comprising a radioresource manager for a user terminal, and linking means for linking tothe interface of the terminal device so as to transfer radio resourceinformation between the mobile station and the user terminal.
 9. Amobile station as claimed in claim 1, further comprising a browser. 10.A dual mode station comprising: control means for controlling transferof information such that in a first mode transfer of information isbetween the mobile station and a mobile communication network, and in asecond mode transfer of information is between the mobile station and asecond communication network; and means for providing radio contactbetween the mobile station and the mobile communication network in boththe first and second modes.
 11. A method for controlling transfer ofinformation in a communication system comprising a mobile communicationnetwork and a second communication network and a dual mode mobilestation capable of communicating with both of said networks, the methodcomprising: providing a first communication link to the interfacebetween the mobile station and the mobile communication network, saidfirst communication link including radio resource management of themobile communication network; providing a second communication link tothe interface between the mobile station and the second communicationnetwork, said second communication link including radio resourcemanagement of the second communication network; and maintaining saidfirst communication link such that the mobile station remains connectedto the mobile communication network, while actual data is carried overthe second communication network.
 12. A method as claimed in claim 11,further comprising: managing radio resources information independentlyof the mode of operation of the mobile station.
 13. A method as claimedin claim 11, further comprising: providing the second communication linkas a low power RF radio resource.
 14. A method as claimed in claim 13,wherein the low power RF is Bluetooth.
 15. A method as claimed in claim11, further comprising: providing call control and mobility managementof the mobile station via the mobile communication network.
 16. Acommunication system comprising a mobile communication network and asecond communication network and a dual mode mobile station capable ofcommunicating with both of said networks, wherein: the mobilecommunication network comprises a base transceiver station emulator forproviding a first communication link to the interface between the mobilestation and the mobile communication network, said first communicationlink including radio resource management of the mobile communicationnetwork; the second communication network comprises a second basetransceiver station for providing a second communication link to theinterface between the mobile station and the second communicationnetwork, said second communication link including radio resourcemanagement of the second communication network; and the mobilecommunication network comprises controlling means for maintaining saidfirst communication link such that the mobile station remains connectedto the mobile communication network, while actual data is carried overthe second communication network.
 17. A communication system as claimedin claim 16, wherein the mobile communication network comprises managingmeans for managing radio resources information independently of the modeof operation of the mobile station.
 18. A communication system asclaimed in claim 16, wherein the second communication link is a lowpower RF radio resource.
 19. A communication system as claimed in claim18, wherein the low power RF is Bluetooth.
 20. A communication system asclaimed in claim 16, wherein call control and mobility management of themobile station is managed via the mobile communication network.